Internal combustible engines require oil distribution to help prevent moving parts from incurring friction damage. Some internal combustion engines include a balance shaft. The balance shaft is configured to reduce vibration generated by the movement of the opposing pistons.
The balance shaft is mechanically coupled to the crankshaft. In some embodiments of the internal combustible engine, the balance shaft includes a balance shaft gear coupled to a crankshaft gear. The crankshaft may further include a plurality of counter weights rotatable about the crankshaft so as to offset secondary vibrations from the actuation of the pistons.
FIG. 1A is a cross-sectional view of a prior art engine assembly 300. The components of the engine assembly are disposed within a crankcase housing 310. The balance shaft 330 is coupled to the crankshaft 320. A balance shaft gear 340 is fixedly mounted to the balance shaft 330 and includes a plurality of teeth engaged with a crankshaft gear 340 having corresponding teeth. The balance shaft gear 330 is disposed in a lower portion of the crankcase housing where oil may reside.
FIG. 1B is a view of FIG. 1A showing the oil distribution within an operating engine assembly 300. FIG. 1B shows how oil at the bottom of the crankcase housing 310 is splattered throughout the upper portion of the crankcase housing 310. In particular, FIG. 1B shows how the balance shaft gear 340 splatters oil by the teeth of the balance shaft gear 340 scooping oil. As the oil is splattered, the oil becomes entrained. It should be appreciated that entrained oil is not suitable for pumping as entrained oil reduces oil pressure which in turn reduces the efficiency of the pump. It should be further appreciated that the reduction in pumping efficiency may in turn reduce the oil distribution to the engine.
Accordingly, a need exists for an engine assembly configured to reduce the amount of oil being splashed within the crankcase so as to help prevent the generation of entrained oil and maintain the pumping efficiency of an oil pump and reduce oil mist escaping from the positive crankcase ventilation system so as to reduce oil consumption.